Nissan GT-R LM NISMO: Hybridized, FWD Le Mans Weapon

Unconventional racing wisdom for Le Mans—seriously unconventional.

TONY SWAN

Feb 11, 2015

After a 16-year absence, Nissan will return to the top class in the Le Mans 24-hour race this year, joining Porsche, Audi, Toyota, and others in the chase for overall victory. Like those three manufacturers' cars, Nissan’s challenger will feature a hybridized powertrain. But the similarity ends right there.

For example, drivers of the Nissan GT-R LM will be sitting behind the power sources, rather than in front of them, peering out over a vast expanse of hood. And all of that power will be vectored to the front wheels, at least as the car is currently configured. Nissan is keeping its options open regarding the possibility of altering the mechanicals to send some of the thrust to the rear wheels. Unlike many race cars, the wheels are wider at the front (13 inches) than the rear (9 inches), the better to put power on the pavement.

Power seems to be an open issue. The internal-combustion component is a twin-turbo 3.0-liter direct-injected V-6, burning gasoline rather than the diesel favored by the other LMP1 heavyweights. Nissan isn’t discussing specifics yet, but output for the engine alone is anticipated to be in the neighborhood of 500 horsepower. However, the engine-development team prioritized efficiency as much as sheer thrust, since the arcane rules laid down for LMP1 hybrids by the sanctioning body—France’s Automobile Club de l’Ouest (ACO)—limit fuel capacity to 68 liters (17.96 gallons). As a consequence, achieving maximum laps per tank is critical, particularly on a long track like the 8.47-mile-long Circuit de la Sarthe.

According to GT-R LM designer Ben Bowlby, the DeltaWing designer for whom thinking outside the box is an everyday activity, the twin-turbo V-6 will burn about 30 percent less fuel than a similar Nissan gasoline engine that ran at Le Mans in 2013. But 500 horsepower is only a fraction of what it will take to turn competitive laps at Le Mans. The balance of the power, expressed in joules, will come from the custom Kinetic Energy Recovery System (KERS) fabricated by Torotrak, which will harvest energy from the front-wheel brakes.

Minding Joules

A joule is a unit of work, equivalent to a newton-meter. And the key to making the Nissan competitive is how many joules it can add to the power equation, or, more accurately, how many megajoules. Megajoules (MJ) are the Catch 22 in the ACO rules for LMP1 hybrids. The ACO formula allows for deployment of a certain number of megajoules per lap, and there are incremental thresholds: 2MJ, 4MJ, 6MJ, and 8MJ. Each threshold reduces the amount of fuel the car will burn to maintain lap times—and increases the thrust available for powering out of corners.

The downside is mass. The bigger the storage capacity of the KERS system, which will reside beneath the driver’s legs, the more it weighs. Minimum weight for the GT-R LM’s class is 880 kilograms—1940 pounds—and, as Bowlby has pointed out, “We’re going to be very challenged to make our weight target when half of the weight of the car is the powertrain.”

This leaves out the mass associated with four-wheel drive. Not to mention the challenge of getting all the hardware lined up. As Bowlby notes, MJ systems aren’t the sort of thing you can buy off the shelf at Pep Boys.

Bowlby and others at Nissan are vague about how much total system output the GT-R LM will bring to the FIA WEC Endurance Championship when it opens on April 12 at Silverstone in England. Estimates place it somewhere in the vicinity of 1250 to 1500 horsepower, down considerably from earlier goals that reached as high as 2000.

Aeromass

Bowlby explains that the front-mid-engine design was conceived to support the front-wheel-drive concept, giving the car a forward weight bias to help the big front tires deliver optimum bite when big megajoule outputs flash into the driveline. The same consideration affected aerodynamic development. Starting with the basic vehicle concept, Bowlby says that “the aero center of pressure, the mass center of gravity, and the tire capacity are all in harmony.”

Aside from an adjustable rear wing, aero specifics—coefficient of drag, frontal area, downforce, and lift—have not been revealed, and they probably will never be. But a good many other specifications have been. For example, the car is 182.9 inches long, 74.8 inches wide, and 40.6 inches tall. The bodywork is carbon composite, the windshield fabricated from polycarbonate with a hard coating.

The suspension is composed of Penske dampers with four-way adjustability and also features a hydraulic rear anti-roll bar. Six-piston calipers squeeze the front brakes, with four-piston calipers at the rear. The brake-by-wire NISMO system is integrated with the KERS function and includes driver-adjustable front-rear bias.

Cosworth supplies the ECU and the controller for the five-speed sequential gearbox, which feeds power to the wheels via a hydraulic limited-slip diff. Tilton supplies the four-plate carbon clutch. Like the brakes, the throttle is drive-by-wire, and the drivetrain includes driver-adjustable traction control. The steering wheel is by NISMO, and the LCD info graphics come from Cosworth.

PlayStation at Speed

Nissan has yet to flesh out its WEC driver lineup, but its first appointee is as innovative as the car itself. That would be young Jann Mardenborough, a 24-year-old hotshoe from Darlington, England. Mardenborough has made his racing bones with the Infiniti Red Bull Racing driver development program in GP3, and he also drove the Nissan LMP2 car at the 2014 Le Mans race.

But his route to a top sports-car ride is unique. It began with Nissan’s GT Academy, which sifted driving talent via performance in video games. Mardenborough’s skill in PS3 was tops in season three of the program, which propelled him into race cars. No karts. No schools.

All in all, Nissan’s Le Mans quest is nothing if not unique. Bowlby calls it his “boldest undertaking” to date. Hmm. How do you say understatement in Japanese?

For more on the GT-R LM NISMO, including an inside look at the making of its Super Bowl commercial, check out the following links from our friends at Road & Track: